Eco-Friendly Fumed Nanosilica@Nanodiamond Hybrid Nanoparticles with Dual Sustainable Self-Healing and Barrier Anticorrosive Performances in Epoxy Coating

Fumed nanosilica@nanodiamond attached by APTES [(3-aminopropyl) triethoxysilane], named FSiO2@sND, was examined as an efficient anticorrosive nanohybrid for epoxy coating. Compared with fumed nanosilica (FSiO2), nanodiamond (ND) moderated the hydrophilic nature of FSiO2@sND and offered additional functional groups to the nanohybrid, i.e., carboxylic groups of ND and functional groups of APTES, while retaining the eco-friendly nature of FSiO2 in the hybrid nanoparticle. The hybrid nanoparticle showed pH-sensitive release behavior in which APTES is released considerably in an alkaline medium, acting as an efficient corrosion inhibitor. A thorough electrochemical impedance spectroscopy (EIS) study of scratched coatings in a 3.5% NaCl solution disclosed that FSiO2@sND nanoparticles (at 0.33 wt % loading) conferred significant active/self-healing anticorrosion properties for the epoxy coatings, thanks to the release of APTES and the presence of carboxylic groups of ND taking part in forming a stable protective film on the substrate. Accordingly, epoxy/FSiO2@sND coatings showed a corrosion improvement efficiency of 138% at an optimum immersion time of 5 h, which was higher than the 96% improvement for epoxy/FSiO2 coating. Epoxy/FSiO2@sND intact coating showed much higher low-frequency impedance, i.e., 7.23 Ω·cm2, compared with epoxy/FSiO2 coating, i.e., 5.44 Ω·cm2, and neat epoxy coating, i.e., 5.71 Ω·cm2, after 22 weeks of immersion in salty solution. This result along with a detailed analysis of EIS data for intact coatings suggested that FSiO2@sND brought about strong barrier anticorrosive performance for epoxy coating. Such behavior was attributed to improved dispersion of nanohybrid in the epoxy matrix, enhanced cross-link density of the epoxy matrix, and improved coating/substrate adhesion caused by APTES and the carboxylic groups of ND.

A review of the design of packing materials for ion chromatography

The development of ion chromatography has made remarkable progress in the past few decades, and it is now widely used for the analysis of common ions and organic compounds. Ion chromatography has many advantages, such as fast, high sensitivity, good selectivity and support for simultaneous analysis of multiple ionic compounds. In order to meet the high requirements of material analysis, new packing materials for ion chromatography with higher sensitivity and selectivity have been developed. In this paper, a lot of knowledge of ion chromatography is reviewed, and the development of ion chromatographic packings in recent years, especially in the last five years, is summarized.

Recent advances and applications of synthetic diamonds in solid-phase extraction and high-performance liquid chromatography

Since the advent of diamond-based adsorbents in the late 1960s, the interest in their use for solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) has steadily increased. This is primarily due to their unique properties, such as extreme chemical and thermal stability, high mechanical strength and biocompatibility, and complex mixed-mode retention mechanisms. Currently, the most commonly used synthetic diamonds in SPE and HPLC are detonation nanodiamonds (DND), high-pressure high-temperature (HPHT) diamonds, and chemical vapour deposition (CVD) diamonds. These diamonds have been either used as individual particles (in both modified and unmodified forms), or for surface modification, or entrapped within composites and core-shell particles to develop new diamond-based adsorbents. These diamond-based adsorbents have been used for a variety of applications, including streamlined proteome analysis; extraction of anions, cations, actinides, uranium, lanthanides, alkaline earth metals, transition metals, and post-transition metals; and development of reversed-phase, normal phase, hydrophilic interaction, ion chromatography, and mixed-mode liquid chromatography columns, to name but a few. These varied applications of different types of diamonds are typically governed by their specific properties. This review discusses the various surface and bulk properties of DND, HPHT diamonds, and CVD diamonds that facilitate or limit their use in different SPE and HPLC based applications.

A phenylenediamine-based carbon dot-modified silica stationary phase for hydrophilic interaction chromatography

Red emitting carbon dots derived from p-phenylenediamine were successfully grafted onto the surface of porous silica spheres which served as a new stationary phase for hydrophilic interaction chromatography with enhanced selectivity.

Nanostructured Silver Coating as a Stationary Phase for Capillary Gas Chromatography

A capillary column coated with nanostructured silver coating was fabricated for gas chromatography. The nanostructured silver coating, about 80-120 nm in thickness, was prepared as the stationary phase via silver mirror reaction, and was characterized by SEM and EDS. The column was evaluated using different types of model analytes, including n-alkanes, n-alcohols, benzenes, and Grob mixture. A baseline separation of ten n-alkanes on the silver column (15 m × 0.20 mm i.d.) was achieved within 3.5 min through the main hydrophobic mechanism. A mixture of six n-alcohols, or another mixture containing three butanol isomers and two octanol isomers, was separated well on the column. The column separated some benzenes containing benzene, toluene, ethylbenzene, p-xylene, o-xylene, styrene, benzaldehyde, and benzyl alcohol. A Grob mixture containing seven analytes was also separated successfully. Based on a multiple retention mechanism such as hydrophobic, dipole-dipole, and dipole-induced dipole interactions, the silver column achieved a good separation of twelve different types of compounds within 2.5 min. The column presented satisfactory separation repeatability with relative standard deviation of retention time between 0.073% and 0.591%. The results indicate that the silver column is promising for gas chromatographic separation.